How do you overload the `

Overloading the Friend Operator << for Template Class [Duplicate]

In programming, you may encounter situations where you want to overload a specific operator to interact with your custom data types or classes. This question explores an issue that arises when attempting to overload the << operator as a friend function for a template class.

The provided code snippet declares a template class Pair with two type parameters T and U. Within this class, there is an attempt to declare the << operator as a friend function that takes an ostream and a Pair instance as parameters. However, the compiler raises a warning about declaring a non-template function, despite the subsequent definition of a template function for the operator.

To resolve this issue, the correct syntax is to specialize the template instance for the << operator instead of declaring it as a general friend function. This is achieved by modifying the declaration as follows:

friend ostream& operator<<<> (ostream&, Pair&);
This declaration specifies that a specialized template instance of the << operator will be defined for the Pair class with the type parameters T and U. It explicitly states that this is a specialization and not a general declaration.
Additionally, the compiler recommendation to add <...> after the function name in the friend declaration is unnecessary in this case because the compiler can infer the type parameters from the template arguments in the definition.
By making these adjustments, the code will compile successfully. Remember that for operator overloading in templates, you need to explicitly specify the template instance being specialized, as shown in the modified declaration.
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